All rodents are gnawers, their ever-growing teeth must be constantly trimmed by this process, which maintains a chisel-like shape to the incisors, which is unique to the rodent family. Rodents chew on roots and will often chew through plastic pipes and electric cables in search of water. It has been shown by field experience and numerous studies that damage by rodents gnawing on small diameter plastic pipes is determined by the hardness of the pipe, for example, polyethylene and flexible polyvinylchloride (PVC) is more likely to be chewed than rigid PVC pipe, and high-density polyethylene pipe is less likely to be damaged than low-density polyethylene pipe. The rodent first feels the pipe with either its incisors or claws, and if it is hard like a rock, it moves away. Thin-walled polyethylene pipes are also damaged by worms and insects.
Damage by gophers, rats and other rodents to polyethylene irrigation pipes and plastic insulated cables are well-known problems. While repellants based on smell may work above ground, below ground they are not effective. Example of such repellants are RODREPEL and REPELLEX. Low-density polyethylene irrigation pipe, tape, ribbon and electrical cables or other devices made of soft plastic or rubber are less expensive and easier to manufacture than high density polyethylene pipe and therefore is more desirable in the irrigation environment. In addition, low-density, soft plastic or rubber irrigation pipe and cables are easier to manipulate and incorporate either above or below ground in the irrigation environment and therefore are more desirable. Consequently, a need exists for a rodent, worm and insect resistant irrigation pipe and cables manufactured from low-density polyethylene, soft plastic or rubber.